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PubMed1979

Production of human lymphocyte mediators after activation with periodate or neuraminidase and galactose oxidase.

Treatment of human mononuclear cells with sodium metaperiodate (NaIO4) or neuraminidase and galactose oxidase (NGO) results in lymphocyte activation and subsequent generation of supernatants rich in migration inhibitory factor (MIF) and leukocyte inhibitory factor (LIF). Preliminary characterization of these mediators by Sephadex G-100 gel filtration suggests that they are similar to antigen- and concanavalin A-induced MIF and LIF, eluting in the 25000 m.w. and 68000 m.w. regions, respectively. The possibility of galactose oxidase carryover into the supernatants has been studied and conditions are described that minimize this eventuality. A method is presented for producing control and lymphokine-rich supernatants both of which have been exposed to identical concentrations of NGO although in the control activation is blocked by the addition of 0.1 M galactose to the incubation. These findings establish NaIO4 and NGO as useful mitogens for generating human lymphokine-rich supernatants that can be used without further purification.

Chromatography, Gel↗
PubMed1986

[Inhibition by alpha-D-galactose of heterophilic antibodies against the antigens of the interstitial connective tissue of the myocardium].

The reaction of heterophile antibodies with interstitial connective tissue cells of bovine myocardium was inhibited with alpha-D-galactose. D-glucose, D-mannose, L-fucose, N-acetylgalactosamine and other monosaccharides demonstrated the lack of inhibitory activity. Disaccharide melibiose and trisaccharide raffinose containing terminal alpha-galactose also had an inhibitory effect on the reaction of sera with bovine myocardium. The results show that heterophile antibodies to heterophile bovine antigen revealed in rheumatic patients' sera differ from antibodies to I and i antigens and T-antibodies, whose specificity is associated with terminal beta-galactose. They also differ from other heterophile antibodies described earlier.

Animals↗
PubMed1989

Enzymatic characterization of UDP-galactose:FdSdG galactosyltransferase in purified liver plasma membrane.

This study yields evidence for the localization of a galactosyltransferase in purified liver plasma membranes, with the following results. The purified plasma membranes contained galactosyltransferases which transfered galactose from UDP-galactose into desialylated-degalactosylated fetuine. A suitable system of glycosylation reaction was defined. It contained: 10 mM Tris-HCl pH 7.4, 5 mM Mn2+, 4 mM NaF. For the assay with exogenous acceptors, 1.6 mg/ml of desialylated-degalactosylated fetuine and 0.1% of triton X-100 were added. The apparent Km values for UDP-galactose were about 10(-5) M. Enzymatic activities required Mn2+. This cation appeared to be a linear non-competitive activator when used at concentrations below 5 mM. Mg2+ and Ca2+ had an inhibitory effect on Mn2+-dependant-galactosyltransferase.

Animals↗
PubMed1989

[Movement of regenerated lens epithelial cells in 50% galactose cataract and an aldose reductase inhibitor].

In experimental galactose cataract of rats, lens fiber cells were gradually destroyed by swelling and liquefaction occurring due to the accumulation of galactitol. In addition to the destruction of lens fiber cells, marked regeneration of lens epithelial cells was universally observed. In this study, we used the technique of 3H-thymidine autoradiography and examined the movement of regenerated (DNA synthesis) lens epithelial cells. On the fourth day from the starting of 50% galactose chow, 3H-thymidine was injected into the anterior chamber. After one week, 3H-thymidine-labelled epithelial cells was observed at the bow region of the equatorial area. After 2 to 4 weeks, labelled cells were found in the regenerated lens fibers of the cortex. After 3 weeks, labelled cells about to be destroyed by swelling and liquefaction were recognized. However, a few labelled cells were still observed in the epithelial cell layer. The same experiments were performed in two groups of normal chow-fed one and 50% galactose + an aldose reductase inhibitor (Statil)-fed one. The movements of 3H-thymidine labelled epithelial cells in the above two groups were almost identical. In addition, the movement of labelled cells was normalized by an aldose reductase inhibitor.

Aldehyde Reductase↗
PubMed1989

Pregnancy-related changes of galactose recognition system on sinusoidal rat liver cells.

We have studied the galactose specific receptor activities of sinusoidal liver cells of pregnant rat from the 13th day of gestation to the 10th day after delivery. Both liver macrophages and endothelial cells modulate the expression of hepatic binding protein during rat pregnancy and lactation. Except for endothelial cells of rats at the 22nd day of gestation, we have measured an overall decrease of binding sites. In addition, in liver macrophages the clustered distribution of galactose specific receptors, which is typical for adult animals, is reduced or completely absent. These results indicate that the galactose specific receptors on non-parenchymal liver cells are modulated in relation with the physiological state of the organ like the asialoglycoprotein receptor of hepatocytes.

Animals↗
PubMed1989

Resonance Raman evidence for tyrosine involvement in the radical site of galactose oxidase.

Resonance Raman data are reported for the redox-activated form of galactose oxidase from Dactylium dendroides. Excitation within the red (659 nm) and blue (457.9 nm) absorption bands leads to strong resonance enhancement of ligated tyrosine vibrational modes at 550, 1170, 1247, 1484, and 1595 cm-1. The ring mode frequencies are unusually low, indicating a decreased bond order in the ring. The spectra clearly differ in both frequencies and relative intensities from those characteristic of known aromatic pi-radicals. Enhancement of tyrosine ring modes on excitation within absorption bands previously associated with the presence of the radical in the active site suggests that the ligated tyrosine residue is present in the radical site and may stabilize this radical species through formation of a charge transfer complex. A dramatically different Raman spectrum is observed for the N3- adduct of galactose oxidase, exhibiting a single strong 1483 cm-1 feature. The intense visible-near IR absorption bands for galactose oxidase may derive from transitions within a charge transfer complex between an aromatic free radical and a tyrosine-copper complex.

Azides↗
PubMedDate not supplied

Ion chromatographic determination of lactose, galactose, and dextrose in grated cheese using pulsed amperometric detection.

A method is presented to determine lactose, galactose, and dextrose in grated cheese using ion chromatography with pulsed amperometric detection (IC/PAD). The method is specific, sensitive, rapid, and precise. Sugar levels as low as 0.01% are detectable, and recoveries ranged from 114% at the 0.1% level to 93.3% at the 2.0% level. The precision expressed as coefficient of variation (CV) was 2.3% for lactose, 2.1% for galactose, and 3.1% for dextrose. Lactose, galactose, and dextrose levels are given for 45 authentic hard cheeses and 26 authentic soft cheeses.

Cheese↗
PubMed1987

Galactose loading tests in patients with hepatocellular carcinoma for the assessment of chemotherapy.

Patients affected by liver cirrhosis with and without hepatocellular carcinoma (HCC) underwent galactose testing for the assessment of both quantitative liver function and effective blood flow. The galactose elimination capacity (GEC), when investigating the former parameter, resulted in being significantly reduced in cirrhotics (29.5%) and in cirrhotics with HCC (42.9%) when compared to controls. The galactose clearance, expressing the effective blood flow through the liver, showed a significant decrease (34.0%) only in the group with superimposed HCC. Our results pointed out a significant impairment of effective hepatic blood flow and an overall reduction of hepatic metabolic activity in the cirrhotics with HCC. These data suggest that lower amounts of chemotherapeutic agents must be given to patients affected by cirrhosis with HCC, especially when dealing with substances mainly metabolized by the liver. On the basis of our results, such a reduction was evaluated to be around 50% of the total dosage.

Albumins↗
PubMed1988

Tissue plasminogen activator is endocytosed by mannose and galactose receptors of rat liver cells.

Experiments were carried out to characterize the specificity of uptake of tPA in rat liver cells. Endocytosis in liver endothelial cells of the native carbohydrate variants of tissue plasminogen activator (tPA), and tPA inactivated by diisopropyl fluorophosphate was found to be competitive, suggesting that the determinant being recognized by these cells is different from the active site. Fibronectin and urokinase, which show partial homology with tPA, did not compete with tPA for uptake in liver endothelial cells. Hyaluronic acid, collagen, or IgG, which are endocytosed by specific receptors in liver endothelial cells, did not interfere with the uptake. Reduced endocytosis by liver endothelial cells was observed with tPA modified in the carbohydrate side chains, suggesting that these structures are important for uptake. Ovalbumin, mannan, mannose, fructose, and EDTA, but not galactose, effectively inhibited uptake in liver endothelial cells of both native and diisopropyl fluorophosphate-inhibited tPA, but had very little effect on the uptake of tPA modified in the carbohydrate side chains. Endocytosis of native tPA by parenchymal cells could be inhibited by galactose, ovalbumin, and EDTA, but not by mannose. These results suggest that endocytosis of tPA by liver endothelial cells and parenchymal cells is mediated by the mannose and galactose receptors, respectively.

Animals↗
PubMed1986

The accumulation of myoinositol and rubidium ions in galactose-exposed rat lens.

When rat lens is incubated in 30 mM galactose overnight, the extent of accumulation of rubidium ions (Rb) and myoinositol (MI) are affected, as well as the Na-K ATPase activity. Rb accumulation and Na-K ATPase activity are only slightly affected compared to the dramatic drop in MI accumulation. These changes are completely abolished by sorbinil, which blocks polyol formation, or by rendering the galactose medium hypertonic to offset the osmotic effect of polyol formation. On the other hand, the addition of excess MI to the galactose medium had no effect on correcting these changes. The results obtained are consistent with the polyol-osmotic theory of sugar cataract formation.

Aldehyde Reductase↗
PubMedDate not supplied

[The specificity of galactokinase induction in rat liver tissue under the effect of galactose].

In liver tissue of rats, a conventional laboratory food of which was substituted for galactose-rich food, the galactokinase activity was increased, but the glucokinase was not affected. In the rats kept on a glucose-rich food the glucokinase (but not the galactokinase) was activated. Hydrocortisone injection induced an increase in tyrosine aminotransferase, but the galactokinase activity was not altered. The data obtained suggest that in rat liver tissue the galactokinase was specifically induced under the effect of galactose. Except for the liver tissue, galactose induced galactokinase in eye crystalline lens; the enzyme activity was not altered in spleen and kidney.

Animals↗
PubMed1987

[Reconstitution of high-affinity galactose transport of Salmonella typhimurium in proteoliposomes: energization by lipoamide and NAD or by the membrane potential; inhibition by ATP].

The binding protein-dependent galactose transport of Salmonella typhimurium has been reconstituted in proteoliposomes made from a partially purified protein fraction (containing the three membrane protein implicated in this transport and a lipoamide dehydrogenase activity) and soybean phospholipids. The reconstitution of galactose transport requires the addition of the purified galactose binding protein. Transport is energized either by reduced lipoamide and NAD or by the membrane potential and is inhibited by ATP.

Adenosine Triphosphate↗
PubMed1988

A polarized epithelial cell mutant deficient in translocation of UDP-galactose into the Golgi complex.

Two lectin-resistant mutants derived from a polarized epithelial cell line have been described (Meiss, H.K., Green, R.F., and Rodriguez-Boulan, E.J. (1982) Mol. Cell. Biol. 2, 1287-1294). One of these mutants, the Madin-Darby canine kidney strain II cell line resistant to Ricinus communis agglutinin (MDCKII-RCAr), has been further characterized, and the biochemical defect leading to its altered phenotype has been determined. MDCKII-RCAr cells are shown to be enriched in cell-surface glycoconjugates bearing terminal N-acetylglucosamine residues by in vitro exogalactosylation and by labeling with fluorescent lectins. Binding assays with a sialic acid-specific lectin reveal a 70-75% reduction in sialylation of cell-surface glycoconjugates. The defect is pleiotropic in nature, affecting glycoproteins as well as glycosphingolipids. Analysis of glycosphingolipids shows a strong reduction of galactose-containing glycosphingolipids. Almost 90% of the glycosphingolipids are identified as glucosyl-ceramide. The mutant is not deficient in galactosyl- and sialytransferase activities. However, Golgi vesicles isolated from MDCKII-RCAr cells translocate UDP-galactose at only 2% of the rate observed for vesicles from wild-type MDCKII cells. The deficiency is specific, because translocation rates of UDP-N-acetylglucosamine and CMP-sialic acid are comparable for vesicles isolated from MDCKII-RCAr cells and wild-type cells. Despite the inability to translocate UDP-galactose into the lumen of the Golgi apparatus, MDCKII-RCAr cells are able to form monolayers with normal apical and basolateral polarity as shown by plasma membrane domain-restricted exogalactosylation.

Animals↗
PubMed1988

Galactose inhibition of ovulation in mice.

Clinical evidence suggests an association between galactosemia and premature ovarian failure. In the present study, adult female mice were fed a diet consisting of 50% galactose for either 2, 4, or 6 weeks. At all times there was a decrease in the normal ovulatory response, as evidenced by a reduction in the number of corpora lutea when compared with controls. Additionally, the exposure of galactose-treated mice to a superovulatory regimen of pregnant mare's serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG) failed to induce an increased ovulatory response. Morphologic alterations, such as the increase in interstitial tissue and the appearance of lipofuscin, coupled with the failure to respond to exogenous gonadotropins, suggest that the reduced ovulatory response may be occurring at the level of the ovary. This effect, however, is reversible with cessation of galactose treatment.

Animals↗
PubMed1987

Effect of amoxicillin on galactose transport across rat small intestine.

The effect of amoxicillin on galactose absorption across rat small intestine was investigated by using in vivo and in vitro techniques. Amoxicillin caused a dose-related, time-dependent, and reversible inhibition in intestinal sugar transport. Intestinal galactose transport was not affected when the drug was perfused in an adjacent loop. Also, intestinal oxygen consumption was not impaired by amoxicillin. Amoxicillin decreased the apparent affinity of galactose for the carrier system, while both its maximum absorptive capacity and the phlorhizin-insensitive component of sugar absorption remained unaltered.

Amoxicillin↗
PubMed1986

Galactose metabolism in male and female rats. I. Blood and urinary differences.

When rats consumed a well-balanced diet containing 30% lactose or 30% glucose-galactose mixture, some differences of metabolic utilization arose between males and females. With lactose, the urinary excretion of lactose, galactose and galactitol was higher in females. With the glucose-galactose mixture, galactosury and galactitolury in males and females increased and were similar; but galactosaemia and galactitolaemia were more important in females.

Animals↗
PubMed1985

D-galactose uptake by snail intestine: competitive inhibition by phlorizin and sodium dependence.

The net entry of galactose into the tissue of snail everted intestinal rings with 2 or 15 minute long incubation periods has been measured. With 10(-4) M phlorizin, the mediated transport is completely blocked while only the passive entry of sugar is produced. Lower concentrations of the glycoside partially inhibit transport according to competitive inhibition kinetics (K1 = 10(-7) M). The transport of galactose is Na+ dependent. In the absence of Na+, transport ceases and the sugar entry can be explained through simple diffusion. With 15 mM Na+ (control 71,4 mM) transport diminishes and a marked increase in the apparent Km with no changes in the Vmax is observed. One mM harmaline completely blocks galactose (0.5 mM) transport. One mM ouabain also makes transport null, but only after tissue preincubation with the inhibitor on the serosal side.

Animals↗
PubMed1973

[Study on the absorption and utilization of D-galactose and D-glucose by liver and muscular tissue in the albino rat].

In order to compare the disposition of D-galactose and D-glucose in various organs of the rat, we have measured the amount of 14C-galactose and 14C-glucose present in the enteric canal, blood, muscle and liver, 2h. after the oral administration of the labelled esoses. Our results show that the two esoses are ebsorbed almost completely and to the same extent by two hours after their administration, Galactose has a longer half-life than glucose, being more slowly utilized in the synthesis of glycogen in liver and muscle.

Animals↗